Agree with the viewpoint that, in principle (all other things being equal, which they probably won't be in reality), there should be no difference between torque stored as inertia in a high mass platter, and torque as applied by the motor -- at least in the moment of initial transient attack. But the dynamics of how the platter recovers lost speed in preparation for the next transient event, or during sustained peaks, may well be different, and maybe could favor the lower-mass/higher-torque model. (And/or also the model of active speed sense-and-control?) Anyway, there are clear advantages of price and ease of placement in not having to get a TT with a platter that's half your body weight. A lighter platter also eases the job requirement of the main bearing. A degree of flywheel effect is certainly desirable in any TT design, but to me there's something dissatisfying about the idea of always resorting to supermassive platters.
I'm not sure I can entirely agree with Johnnantais on a few other things, but he probably knows more about it than me. Still, I can't reconcile the blanket assertion that a motor turning at 1,500 RPM is intrinsically better than a motor turning at 33 1/3 RPM -- that high rpm "by itself" tends to "smooth out" speed imperfections. If we assume the same level (amplitude) of vibrational contamination for the sake of argument, the only difference, it seems to me, will be in the frequency and its harmonics, which will also alter the spectrum of intermodulation products. That will change the sound, but I don't know which one is better, or what might constitute the "ideal" RPM or frequency to superimpose upon the music signal (none would be nice). But I doubt it's as simple as saying "higher is better", especially when only one fundamental falls within the audioband (1,500 RPM = 25Hz, while 33 1/3 RPM is only about 1/2Hz). I'm not exactly sure if all this stuff is pertinent to the topic at hand though, maybe an engineer or physicist could elaborate further.
If we stipulate (correctly, I hope) that high torque is what pushes the platter through dynamic passages, then as far as I know, in electric motors lower RPM = higher torque (larger motor diameter does too, which DD's also generally have). I have zero experience with the big idler-drivers mentioned, so I'm guessing that for their motors to be both high-speed and high-torque, they must also be relatively large and powerful (higher amp). If so, wouldn't that increase the amplitude of vibrations vs. a lower-speed, lower-amp motor with equivalent torque? Obviously there will be a lot of other variables regarding how any two motors in question are made, but I wonder in principle.
However, it is undeniably true that the faster you spin anything that's not in perfect balance, the more violence will be imparted by its shaking. Can a motor be perfectly balanced? If so, I guess we wouldn't need to have this discussion. So, adding it up, I can't buy the notion that higher motor RPM's are somehow "better" for TT performance. I've always assumed one of the strengths of DD was the low-RPM motor: high-torque, low amplitude of vibration, low frequency of vibration. Somebody please point out the error of my thinking if I'm wrong. Absent the RPM argument, I haven't yet detected the theoretical case for why idler-wheel drive should be intrinsically superior to direct-drive. That it may prove subjectively superior among certain 'tables auditioned by certain listeners is another question.
Maybe I'm way off base somewhere here, but speed performance is measureable -- you don't have to depend solely on subjective listening impressions to find out about this particular factor. Does anyone know that idler-drive tables can have better wow & flutter numbers under dynamic playing conditions than a good quartz/PLL controlled DD? Are there any constraints that prevent a DD motor from being made just as powerful as for an idler-drive, if that's what one wanted? (Magnetic interference with the cartridge, perhaps? The platter's shielding ability may be limited, but I don't know -- I thought the Rockport DD was supposed to be terrifically powerful and nearly impossible to deviate the speed of. If you pay enough, you can get a high-torque/high-mass DD table, with the electronic control to harness both.)
To me, DD does seem to have several intrinsic theoretical advantages. One is that the motive force is applied without physical contact of the platter. If you use a belt or a wheel to transmit force to the platter, it must result in some added degree of motional friction, which must produce a characteristic resonance, much like road noise in tires (okay, so it's probably more like urethane skate wheels on polished marble tile, but the principle still applies -- it's still not silent).
Another is the fact that there's only one bearing, the ubiquitous main bearing. In any design with a separately housed motor, that motor must have its own bearings in addition to the necessary main platter bearing. Then there's shafts and pulleys or wheels -- they won't be perfectly concentric. DD does away with powered driveshafts, pulleys, and/or wheels.
I tend to think simpler is better (simpler, but not too simple! ;^) A TT doesn't get any simpler, mechanically speaking, than a DD: the plinth is the stator, and the platter is the rotor. In any other arrangement, the separate motor can and will move in relation to the platter, which causes variation in platter speed. In a DD the motor can't move relative to the platter, since the platter is itself one half of the motor.
Another thing: I don't know if this absolutely has to be the case, but as far as I know only DD's incorporate electronic sensing and control of platter speed directly, rather than control of motor speed (but typically without sensing, I believe) with a somewhat flexible linkage in between it and the platter. I know which arrangement seems like it would be better to me, but I'm open to arguments. Again, though, the results can be measured.
Along those same lines, there's the issue of how correct speed is established in the first place. With a PLL sensing system in place, it's easy to add calibration to a quartz crystal reference, a very much higher and more constant frequency than (and totally independent of variations in) the AC powerline. Who wouldn't want that if you can have it? And again, the results are measurable.
I've often seen an argument against PLL-controlled DD's that usually goes like this: They are constantly "hunting and pecking" for the correct speed, but never settle on it. I have never understood this. Any electric motor operates in what is termed a "kick and coast" fashion, dependent on the number of poles. More poles would seem to be obviously better than fewer poles, but I don't know that the number of poles possible is in any way linked to or limited by drive method. Anyway, it seems to me it's primarily this kick and coast phenomenon, dynamic stylus drag aside, that's primarily responsible for any TT not constantly rotating at exactly the correct speed, no matter how it's driven. Why this is blamed on implementing a PLL is something I want to know.
Another thing I want to know is why DD is often portrayed as constituting a "rigid coupling" between the motor and the platter (never mind that this doesn't make any semantic sense, since in a DD the platter is in fact part of the motor). At times I almost get the feeling that some audiophiles who haven't owned a DD visualize it as simply consisting of a belt-drive type motor -- meaning a self-contained unit with a housing and a protruding driveshaft -- with the platter stuck on the end of the shaft instead of having a pulley and belt in between. (If that describes anybody reading this, go to the website Viridian linked above and look at the platter-off pics of the SP-10.) Anyway, "rigid coupling" seems to imply that the platter can't "slip", which of course is 180 degrees opposite of the truth -- any DJ knows that only in a DD can the platter be freely spun manually when not under power, or manually deviated with precision from constant speed when under power, from which it will rebound when released. ("Rigid coupling" also implies vibrational transfer, which again to me is a conception misappropriated from the paradigm of separately-housed, self-contained motors physically linked to platters and plinths by compliant couplings.)
As I understand it, in typical audiophile belt-drivers, the elasticity of the belt, combined with the inertia of the massive platter, is supposed to mitigate the kick'n'coast speed variation from the motor. Of course this can't simply be "gotten rid of" -- the elasticity and inertia combine to spread its effects out in time, reducing the amplitude peaks, effectively averaging the variation in speed. Well, platters in DD's also have mass. The "slippage" and subsequent rebound that I described when a drag or an energy input is applied, isn't that functionally equivalent to belt elasticity? It seems to me that in a correctly designed DD, the PLL sense-and-control system, combined with the platter inertia and the natural ability of the platter to smoothly and infinitely vary from constant speed and then rebound without introducing mechanical friction, can constitute exactly the same kind of "averaging" mechanism that smoothes the kick and coast impulses in a belt-driver. The difference is you don't need a supermassive platter or the attendent pitfalls of a belt/pulley/separate-motor system to do it when you've got active speed control working for you.
I know many audiophiles regard the notion of any "servo" or "feedback" type of operation as something they're allergic to, whether it's negative feedback in amplifiers or servo control of subwoofers. As the saying goes, you can't correct something that's already happened. Same for many active vs. passive questions (though not always). I also know many engineers would argue with this attitude and say it's not that simple or universal a truth, that there can be well-implemented applications for feedback-type mechanisms that don't harm sonics in unintended ways.
I can't comment on all that stuff, or its applicability to DD TT design, with any authority (though I don't recall anybody saying that adding an outboard speed controller to their belt-drive TT made it sound worse). Yeah, I own a DD [KAB-modded SL-1200], but like I've said before, I lack the comparitive expeience to make pronouncements about relative superiority. But I also note, with no real satisfaction, that probably no audiophile, no matter how experienced, has ever had the opportunity to compare two turntables whose only difference was method of drive. As we all know, there's a host of other factors which affect TT sonics besides drive type. I also acknowledge that measurements, such as I touted above, often don't tell the whole story sonically speaking (which simply means we need other, better measurements to correlate with what we hear).
More important though are, as I see it, two questions: The one Drubin asks, i.e., do any of the DD's available in the moderate price range (current or restored) warrant consideration over the entry-level and next-tier belt-drive audiophile standbys (none of which are terribly massive due to their reasonable cost)? And the one Macrojack wants to know: Is it time for high end TT makers and audiophiles alike to reconsider the relative merits of the DD option -- could it be exploited to make even better tables than are generally available right now (and if so, at an attainable cost)? I admit I don't know the answer to the first, but feel the second has got to be a yes if at all possible. |
The universality of torque aside, Walker's cut-belt demonstration was a bit of circus stunt. Of course the pitch and tempo of the record dropped during the 20 seconds -- that's a fact of nature -- it just did so slowly and not very much, so nobody noticed through their surprise. If they didn't notice that, then they didn't notice whatever effects of dynamic stylus drag were superimposed on that -- not only because of shock and awe, but because there was no reason for those effects to have changed much before and after the cutting of the belt. The massively heavy platter minimized those effects before the belt was cut, not the motor, and removing power didn't change that. Whatever dynamic speed modulation by the stylus sounds like, it couldn't be a gross effect, it probably manifests as a subtle alteration of textures or something, maybe a bit of clouding of the soundstage, who knows. Hell, there are ways in which you could predict *any* turntable would sound *better* without its motor interfering, if only they all could keep spinning away like the Walker. (Maybe cutting the damn belt even granted it some of the virtues of direct-drive for a time ;^) Point is, there was never any question that an 80lb. platter on an air bearing for $20K+ could help overcome dynamic stylus drag, the real question is if that's the only way, or even the best way. (I've always assumed the really massive platter jobs must have very low flutter but rather high albeit long-period wow, and maybe that's a smart tradeoff.) Or if any of that matters to the sound nearly as much as the resonant characteristics of the turntable -- if not, then use any drive method, just make sure the thing has good vibrations. |
Paul: I agree that the remarkable longevity and popularity of the SL-1200 says exactly nothing about either the worth of that machine to audiophiles, or the worth of DD in general to audiophiles. Now, that fact may say more about audiophiles than about DD (or the SL-1200), but the argument's a false sylogism nonetheless. Granted, perhaps not a lot of products without some sort of fundamental merit do as well over decades as the 1200, but a few do -- witness the Bose 901. But the 1200's endurance springs mostly from people who must depend on it in a professional context, so that the machine has its virtues is uncontested; the question is whether one of those virtues is actually sound quality. I have my inexpert opinion on that, but no "bubble" to burst, trust me, and I do not "bash" BD. If you count my response among those you classify as not being sensible or coherent, then that's your privilege.
So what we mostly have are reports from guys who've owned both. It seems noteworthy to me that among the A-goners who've given good DD a chance and also have experience with good BD, I don't think there are any who dismiss DD out of hand, and a few who specifically extoll the potential of the 1200. (If you want to take Psychicanimal off the table from the start, be my guest; we all know where [and how] Francisco stands, and still life goes on.) In the final analysis, online anecdotes mean less to me than what I hear in my living room, and that I find almost entirely satisfactory and beautiful, especially since the KAB mods. Which shouldn't necessarily say anything to you. Anyway, regardless of the motor/drive system, the 1200 still can't sound better than the basic competence of its plinth, platter, bearing, and tonearm, which *ought* to mean it can't bat in the same league as the big boys (but not because any of those things, save perhaps the platter, is notably deficient IMO). But please feel free to take a stab at any of the theoretical points in favor of DD I raised above. |
Macrojack: Your last post, it seems to me, actually bears little relation to the question you appeared to ask at the top (reread it), or the debate you seem to have been encouraging since. I think a discussion of theoretical potential and pitfalls is totally appropriate, and in many ways a good chew over theory is the best thing you can read on a forum like this. It can teach you new ways of thinking about what you hear. If you expect to settle anything by people recounting their personal experiences and opinions, you're probably going to be disappointed. Online forums are about discussion of audio and batting around of ideas in addition to experience and opinions, and the whole activity is an entirely different animal from actually listening to music or gear. In any case, there are too many people here lacking both the carts and the horses to put one before the other... ;^) |
Raul: Wouldn't the rumble specs, at least, be somewhat dependent on the plinth made for a deck-mount DD?
Anyway, whatever one thinks of Michael Fremer, to me it's interesting that a guy who's critically auditioned that many turntables, and proclaimed the direct-drive Rockport Sirius to be the uncontested best at the time he had it, later decided the belt-drive SME 30 (at about 1/3 the price without arm) equalled or slightly bettered it (with a Graham arm fitted). This is notable not only from the DD vs. BD perspective, but because the Rockport had an integral linear-tracking arm (Fremer has in the past has extolled not only the theoretical but the actual benefits of linear arms if properly executed), air bearings all around, an integral active isolation stand, the more complex motor controller, and was maybe 4-5 times as massive -- none of the which the well-executed but by comparison conceptually basic SME could match on paper. The Rockport may indeed have the better specs -- I don't know that we know, but anyway at a certain point a few more -dB or a slightly lower % may not matter in practical terms -- but for all its engineering heroism, if it doesn't sound clearly superior at its much higher price, which TT is ultimately the better design? And why would a designer then need to go to the trouble and expense of making a direct-drive system in this day and age?
To me the real-world value of DD might be where it is right now on my gear rack: a relatively inexpensive, highly durable, low-maintainance, operationally flexible, speed-accurate, good-sounding TT for not a lot of money, that probably has significantly better specs than any belt-driver in its price range. Which drive method is allegedly "superior" at the top end of the food chain is a debate for others, and hypothetically interesting as the question may be, the evidence could point toward factors other than drive method ruling the roost at that level. |
Dan, I wrote this dreadfully huge post disagreeing with your presumption that static inaccuracy in baseline speed is more of a factor than dynamic micro-speed variations. I don't want to post it the way it is, so I'm just saying so, and we'll see if I ever elaborate ;^) |
Raul: I wouldn't know about the sound quality of relatively inexpensive DD's competing beyond their price range (though you might), I was only stating about their speed accuracy and precision. But a caveat has to be acknowledged: published speed distortion specs only deal with combined gross levels, leaving us in the dark about spectral and temporal character. The possibility exists for one TT to have lower measured speed distortion than another, but of a sonically nastier nature. |
Hold up, I think both both TWL and Macrojack have a couple things wrong here (not that I don't agree with most of the gist of what Tom has said -- I think I said some of the same stuff myself above :-) "...direct drive motors generally (and I use that word advisedly) use their drive shaft as the main bearing, which typically does not have the precision tolerances of a belt-drive system's main bearing..." I believe this is a common misconception, which I talked about in my first post to this thread. I may not always know about "generally", but specifically, a DD like my SL-1200 >>does not have a drive shaft<<. The main bearing is similar to the main bearing in any conventional BD, passive meaning unpowered. The motive force to rotate the platter is applied purely by touchless electro-magnetic impulse -- no shafts, wheels or of course belts involved. (Please also see my first post.) "...Upon looking at the design of my Technics DD, I see that there is no main bearing per se but rather a broad based rotor/stator interface. The notion of that being rocked or deviated from its center seems remote given its diameter, mass and magnetic hold. After all it isn't a pencil point on a hard disk balancing a 12 inch diameter spinning disk. With the Technics table the motor is about 4 inches in diameter and in the case of the SP-10 it is screwed to the motor assembly..." I think maybe you're being fooled by the appearance of the TT with the platter off. If the SP-10 is anything like an SL-1200, the platter fits over the conically-tapered brass sleeve which forms the base of the spindle, which is integral to the main bearing. When you remove the platter, the spindle is therefore left behind -- you can rotate it by hand. That is the main bearing. What you're describing as 4" in diameter is the stator assembly, which is not "screwed to the motor assembly" as you put it (not sure if you meant to write it that way, since it does't make much semantic sense), but bolted to the cast aluminum chassis, the bearing housing of which you can see centrally located within the stator ring at the base of the spindle/bearing. (Again, if it's anything like the SL-1200 -- please let me know if I am wrong in anyway in translating this arrangement to the SL-10.) I would recommend anyone fuzzy about the details who really wants to get a feel for how this works to take a trip down to your local pro-sound shop that sells DJ gear and ask to see their display SL-1200 with its platter removed. (With the power turned off, place thumbs or fingers in the opposing holes provided for this purpose, alternate gently lifting one side and then the other to unseat and then carefully lift straight up). Everything I'm talking about should become very clear. |
I don't think a SL-1200 has a "looser bearing structure" than a BD. I haven't used an SP-10 in over 20 years though, and never looked under the hood of one. The Mk.II pictures on this page, though clearly not the same as my SL-1200, still look to me as if there is a conventional central bearing and no drive-shaft. But on this one, there is a difference noted between the SP-10 Mk.II and Mk.III, with the Mk.II described as having an enclosed motor with what sounds like a sub-platter, vs. the Mk.III's construction which is more similar to the SL-1200. It's still not clear to me, however, whether in the Mk.II the power is actually applied to a drive-shaft, or whether there is more than one central bearing. My assumption is that in any case where torque is transmitted via a shaft, there must be at least two bearings (as in a BD TT, a motor bearing and a platter bearing). I'm inclined to view the subplatter as being a part of the top platter, and regard the spindle shaft as not being called upon to transmit the twisting force, but I could be wrong, or the difference could be mostly academic. Maybe the more important point is that the motor turns at a low 1:1 speed (33 1/3 or 45 RPM) and is a rigid part of the chassis. The latter means there can be no relative motion between the motor and the platter. The former means torque will be naturally high and vibration naturally low. Here is an archived thread that has some more interesting comments, including from Twl. |
Here's something that's always made me wonder. Folks talk about quartz/PLL-controlled DD as constantly "hunting" for the correct speed, or attempting to compensate for deviations after they've happened.
What I'd like to know is this: In a BD, I'd assume that the "kick and coast" action of the motor, or any dynamic drag flucuation caused to the platter, would cause the elastic belt to be stretched a bit on one side and relaxed on the other, because then the drive-pulley and the platter would be turning at slightly different speeds. The belt of course would attempt to regain a state of equilibrium in tension, but this would set up an oscillation between sides that would take a while to die out, before which another disturbing discrepancy would have come along, etc. So the belt would constantly be in a state of "hunting" for the correct speed, n'est-ce pas?
On an SL-1200 there is a built-in strobe, so you can see speed deviation and recovery behavior. If you use your finger or a brush to momentarily apply some extra friction to the turning platter (enough to noticably slow the platter -- in other words hundreds of times more friction than a stylus playing a record could ever apply), it will come back up to speed in a controlled, deliberate fashion without visible overshoot or oscillation.
If you put a strobe on a BD and do the same thing, does it appear to behave the same way, or is there some degree of "bouncing around" visible in its recovery behavior? This may be a "trick" question -- any differences might well be too small and/or fast to be visible either way. |
Raul: I think your focus on speed-accuracy may be overstated. IMO speed-stability is the more important factor, beyond a certain point of competence concerning accuracy. Accuracy isn't that hard to achieve, stability is.
Caterham1700: Those figures would appear to confirm that implementation is a lot more important than classification, but it would be nice to know exactly what those numbers represent of terms of how the test was made and the data assessed. I continue to strongly suspect that the *nature* of a TT's speed distortion has got to be at least as important as its overall percentage level, just as in amplifier harmonic distortion. And that beyond some minimum level of speed-stability competence, resonant behavior might be more sonically significant.
Teres' last post prompted a thought: In theory, shouldn't the ultimate goal for transcribing what's on a record be to duplicate whatever speed distortions are inscribed in the grooves by the cutting lathe? If a TT slows a bit when it encounters increased stylus drag, then a lathe must also slow when it cuts more highly modulated passages into the blank lacquer. To read the information as accurately as possible, the playback should read those grooves with speed distortions that correlate with how it was cut. This would seem to be argument in favor of regarding dynamic stylus drag in TT's as being more benign than is usually supposed, perhaps even beneficial in the right porportion. |
No. Think about it again :-) |
MJ and V: Obviously we can't achieve a correct 1:1 correspondence, or probably even seek one realistically speaking. (Although if that were the goal, then you could make the argument that going with a Technics SP which used the same motor/controller as a Matsushita disk-cutter would be a reasonable strategy. However, lacquers aren't the same as vinyl, cutter-heads aren't the same as cartridges, and of course inscribing a groove isn't the same as following one.) The real point may be that, even were we able to achieve "perfect" playback with zero speed distortion (which we can't), if the record weren't cut the same way, you'd still wind up with speed distortion. Boiled down: You'll always have speed distortion. But we already knew that.
As to Viridian's observation, if our theoretical turntable suffers less dynamic drag on transients than the cutting lathe (maybe not as unreasonable an assumption as it might seem, given the presumably much greater frictional resistance encountered by a cutting-head in inscribing the groove as opposed to a stylus merely reading it), then pitches will go slightly sharp on transients. If the turntable suffers more dynamic drag than the lathe on the other hand, then transient pitches will go slightly flat. All in all though, I don't think it's completely unreasonable to speculate that these speed distortions at the mastering and playback ends might indeed have some rough natural correspondence which tends to mitigate the problem more than exacerbate it. |
Expounding a bit: Viridian, your last question I think may really concern phase. You might be thinking of "flanging" as an analogy, or the way loudspeakers behave regarding crossovers and multiple drivers or reflective room surfaces. If so, that would not apply to this situation, it seems to me -- that sort of reinforcement/cancellation phenomana requires mixing of more than one sound source, which I think the encode/decode of vinyl playback doesn't qualify as. You are right that pitches are affected, and the resulting pitch distortions will derive from addition and subtraction, but I don't believe there is any constructive/destructive reinforcement going on as I understand the concept. For instance, to "flange" as they originally did in the recording studio, you need two reels of tape both with the same signal recorded on them, played back in synchrony, which is then modified by applying friction via the engineer's hands to the reels' flanges. But if you recorded one reel of tape while altering the pitch by applying drag to the flange, and then played that pitch-altered reel back while doing the same thing again, the "flanging" effect would not be the result, just further pitch distortion. |
Anybody seen the new Grand Prix Audio Monaco DD described in April's "Analog Corner" CES report? Quothe Fremer: "Ultra-compact...magnesium platter...bronze flywheel...CPU-controlled...5,000-point optical reader...platter which is also the rotor (sound familiar?)...only mechanical attactment point is the bearing, no contact in the horizontal plane...composite polymer-damped plinth...aluminum billet armboard...$15-20K? Albert? You getting one of these for review to go with those racks? Now there would be a DD vs. BD showdown for you. |
Raul: "BM" for "brain-masturbation"? (Well, I guess those who've got... BTW, "BM" is already taken my man, or didn't you know? Or maybe you meant it that way? Classy!)
Look, it's regrettable you can't handle being disagreed with in good grace, but I stand by my comments. Speed-stability is the crucial issue, not speed-accuracy within reasonable limits. IMO.
Of course it's better to be more accurate, and 0.001% is speed-accurate. So is 0.01%. So is 0.1% -- that equals a mere 1Hz error for a 1,000Hz tone, which if constant has zero perceptible impact on the listening experience. Even a 1% static error alters the essential character of the music only very slightly, and even then usually only in direct comparison with the correct speed. 0.001% vs. 0.002% baseline inaccuracy means nothing, you cannot hear the difference. And it's not even worth getting into how valid or comparable the claimed specs you're throwing around here are anyway -- probably half of those quoted mean nothing as well. Judging from your posts, you seem to think that listing specs somehow qualifies as "scientific" as you say, or is a substitute for making a cogent argument. Guess we could call that "SM" if it hadn't already been taken. "With all respect", Ciao. |
Raul: Sorry, but the only thing one can "judge" from that list is that you spent much time and effort collating those numbers. You can list claimed specs til the cows come home however, but for many reasons it still doesn't amount to an argument (scientific or otherwise), or illuminate anything about what we hear or which drive method is "best". It just doesn't. Appreciate your witholding the "wrath of Raul" however!
Doug: Hey baby, don't go all brain-masturbatory on us now! ;^) I have to side with SDT99 and Jyprez on this one. I too have never understood the 'damage to harmonic relationships' argument, since everything changes proportionally and in unison. A 1% deviation from the way something was performed on a recording is still well within the range of variation in tempo and tuning encountered in live performance, as well as the unique harmonic structures possessed by individual examples of instruments. Personally, I think you usually have to go to a 2% - 3% deviation for the music to start sounding a bit 'funny' in absolute terms, but I grant you that system fidelity and program material selection will have an impact on that threshold. I can't quibble with your opinion of what you hear, but my own suspicion is that if you didn't play a recording with which you were already familiar, or didn't play one in close proximity to hearing it at the correct speed, a 1% steady-state error, while audible in relative terms, would not call attention to itself in isolation. This is something that of course could be blind-tested for pretty easily, and I'd lay money on getting negative results. |
Cool. Of course, even with a linear arm there'd still be the difference of air-bearings vs. conventional bearings. And at this level, I'd frankly expect resonant signature to trump drive type overall (you'd think that would be a strong point for anything from Grand Prix), but suspect each will have its strengths. If it's even close to a draw though, that would tend to support the view that DD can't be dismissed on nothing but facile principle. If it's not even in close in favor of the Walker however, it would probably be unfair to draw general conclusions regarding drive type. |
Dopogue: That thought had occurred to me as well, and I think it's a perfectly legit observation. But I'm probably more immature than you ;^)
Macrojack: If I say I didn't think we were "bickering", will it sound like bickering? |
Raul: I don't want to beat, strangle, shoot, drown, and blow up a dead horse, BUT... > I don't excpect you to be familiar with my collected works on Audiogon, but anyone who's read me around here over the years could tell you that I am hardly a pure subjectivist. I often raise questions concerning what it is audiophiles think they hear, what they prefer, how they arrive at those subjective determintations, and the influence of technical ignorance and psychology. I'm all for whatever degree of objectivity is obtainable or practical.
> I do think measurements are important, for audiophiles both as a check on quality and as information to help us understand what we hear, and of course for product designers they are essential tools of the trade Having said that, I also think numbers can be misleading under several circumstances, such as... > If there is little or no correlelation established between what is being measured and what we can hear
> If there is no test devised capable of measuring some aspect of what we can hear
> If the tests performed omit covering some measureable aspects which probably do correlate with what we can hear
> If a test measures something that bears little useful resemblence to playing music
> If the measurements we are comparing are those claimed by manufacturers under unknown or unverifiable test conditions, not independently obtained using a uniform test procedure
> When tests that measure the wrong thing, or fail to measure the right thing, are misrepresented as the authoritative determinants of performance When it comes to the turntable specs you've listed, there are several pitfalls evident: > These are manufacturer numbers, unverifiable and taken under unknown test conditions which it is reasonable to assume were not always uniform
> Even if all the numbers were valid, they may not be representive of all samples of these products that we might audition or pertain under all real-world conditions
> We do not know whether or to what degree the small differences between the numbers correlate with audible performance
> Numbers for wow, flutter, and rumble do not define the universe of possible quantifiers of turntable performance, they only relate to certain aspects of it
> And in any case, wow & flutter and rumble numbers tell us only about aggregate quantity -- nothing about the actual spectral or temporal qualities of the distortions. So, identical numbers for two different turntables can in fact represent different behavior and therefore possibly sound. You wrote: "From a pure objective approach, the 'numbers' are what define which audio device is better, not if we can hear those 'numbers'." This is a fallacy, for some of the reasons I've listed above, and even if you discount the importance of being able to hear everything that is measureable. If you believe that measurements always objectively define what is better, then you simply don't know enough about the numbers, what they mean or might mean, and what they don't mean or might not mean. As the movie said, "A man's got to know his limitations", and that goes for a man's numbers too. |
I think that might be an actionable offense in many states... |
"...in the TT subject and from the objective approach it is a fact that we can only 'work' with the 'numbers' that are on hand: there are no others!" There could be others, they're just not taken or not published. But I presume there's no technical reason, beyond a lack of will or resources, why turntable reviews couldn't include detailed measurements of speed distortions, noise, and resonant behavior that take into account spectra and duration, not just simple amplitude, as well as frequency and transient response/distortion at the output. The status quo however is that turntable reviews (and cartridge and tonearm reviews) include no measured test results whatsoever. This is unfortunate, because I believe there can be a salutory effect on the product marketplace stemming from public accountability for technical performance claims and the availability of comparison data. It might be interesting if Teres would be willing to share with us some idea of what kinds of measurements are taken as part of a manufacturer's design and testing process that aren't normally published for consumer consumption. |
"Makes me wonder what we're hearing though" IMO, either you're... 1) Not hearing what you expect to hear, based on extensive personal experience with the records tested 2) Hearing what there is to hear, based on the fact that you just played the record at the correct speed, and know which one is which 3) Hearing what you do expect to hear, based on your preconceptions about what effect will be wrought by a 1% speed change ...or some combo of the above. The acid test of this perception would be to use unfamiliar recordings and a helper, having them played back for you blind at both the correct speed and 1% off, to see whether you can consistently identify which playback is correct and which is fast or slow. I think this would probably be an exercise in futility though, maybe even at 2% in many instances, or even higher with some other types of music. |
Johnnantais: "types of audiophile: those who love the equipment for the music they can produce, placing the music/software first, are called "melomane"; and those who love the equipment for the detail/information it can extract, thus focusing on the equipment more than the music/software" Maybe it's just the way you put it in translation, but to me this is a false distinction. All are audiophiles because all "love the equipment". (Personlly, I think I've passed the point where I can love my equipment for its own sake, perhaps only doing so when it's playing music the way I want it to, but maybe I just own the wrong equipment.) To me, the amount of information your equipment can extract, as you put it, from your recordings is a good 75% of the reason for doing any of this in the first place, with the other 25% falling to that equipment's intrinsic "sound" which is not on the recording. At least that's if we're doing this right. "I see this thread keeps on going!" Oh yeah, you're a great one to talk! ;^) |
"If any of you guys would meet me in person and looked at the palms of my hands you'd understand"
Uh, that's OK, thanks anyway...
But getting back to the subject at "hand" (ahem), as far as I know there's nothing about implementing a quartz-referenced PLL that couldn't be done in turntables using something other than direct-drive, if one wanted or needed to. |
Tom: "it is patently apparent that most here do not even differentiate between the very different nature of wow or flutter components of these speed variations. Or what ramifications are involved with either of those variation types, as regards our hearing sensitivity" I think "most" is "patently" not the word to describe the number of posters on this thread who actually disagree with your position here. "Are we going to extrapolate that all forms of that type of drive system are then superior to all other forms? Or that no other type of drive system can compete, even at various levels of price?" Isn't that basically what happened with belt-drive? "are we going to blindly fly out and buy some form of that drive system, like lemmings over the cliff?" Isn't that basically what happened with belt-drive? I appreciate your arguments and knowledge, and yes, the question asked in the thread-head is maybe a bit overstated in order to be provocative, but IMO defending belt-drive doesn't require setting up a straw man. I will be interested to learn what you think of the Teres DD when the time comes, even if you might not be a customer for one. |
I don't disagree with any of what Tom has said here, but I do think it would be reactionary to suppose that there is a looming "specs war" afoot regarding turntables. First of all, almost the entire market today for the type of turntables we are talking about consists of audiophiles, and that is not analogous to the situation with mass-market amps in the 70's. (In fact, I believe I'm correct in saying that the THD wars were one of the driving forces behind the true emergence of "the high end" as an alternative, and essentially separate, market for audiophiles.)
Secondly, just because specs were abused or misused once, and we learned to be wary of them, doesn't mean that all measurements are worthless (not that Tom said they were). The wow & flutter measurement could certainly stand some improvement as a protocol, but there's nothing wrong with the idea of meausuring turntable speed-distortion, both quantitatively and qualitatively, and trying to correlate that with audible performance and manufacturing and design practices.
And I think there's no quibbling that in theory, a turntable with lower and/or more benign speed-distortions is better *in that respect* than one with higher and/or more malign speed-distortions. Unlike with amp THD, I don't think there's anybody ready to argue that certain kinds of TT speed-distortions are actually euphonic or restorative in some way, or that designing to lower them will necessarily compromise some other area of performance. (In fact, all ultra-premium TT's are ostensibly designed to minimize speed-distortions, whether they succeed or not.)
Also, there's a difference between independent testing and "specs", given by manufacturers and often not worth the paper they're printed on -- especially regarding analog transducers (think speakers) -- in terms of reliability, stating of parameters, or use of a consistent industry protocol. Since turntables (and cartridges) have become such an essential feature of the audiophile landscape once again, the fact that none of these often-expensive components gets measured seems a dereliction of duty by the audiophile press. (Well, I guess by Stereophile anyway, but it seems unfair to single them out just because they're almost the only audiophile publication remaining that tests for anything at all anymore.) I think it would give particular insight to test turntable resonance, showing spectral distribution, amplitude and duration of inherent modes, and resistance to external stimulus. |
"62 Hz, 89 rpm, 16%. WOW!" LOL!
But: "The existing stock of affordable DD tables is small and stable and the concensus here says that mass produced DD will never again be seen."
The stock of new SL-1200's is virtually unlimited and will be mass-produced seemingly forever. |
I was sincere in my question to Teres -- not pessimistic, only a bit prodding. I think it's possible to do both (good marketing and good design; there's nothing wrong with the former as long as it serves the latter), I just sense he's downplaying the reasons why Teres is, in your words, taking "a huge gamble". For all the reasons you list why this wouldn't be undertaken lightly, it's hard to conclude anything other than that Teres does believe that DD holds more promise in some important way(s). I want to know why. |
Teres: You *elected* to implement it with direct-drive. Why? Marketing (which I think may be a good move in a crowded BD universe), and/or something more?
PA: You lost me, I don't understand the meaning of your response to my wisecrack (which was only in reference to "watching women's palms" -- intended as a joke, though I'm guessing you're not joking about anything...) |
Thanks Teres for elaborating. Guess it's a good thing you feel your product development results have affirmed the theoretical reasoning which preceded them :-)
On somewhat of a sidetrack note, let me toss out a bit of theoretical reasoning of my own. I think almost everbody in the business could have it backwards in placing substantial platter mass out near the rim. I know why it's done, but suspect that in a different sense it might be a disease worse than the cure. IMO it could be much better from a resonance standpoint to concentrate whatever mass is required for inertial effect as close to the bearing axis as possible and make the outer regions as light as practical. I understand this would entail use of greater mass overall if one wanted to achieve an equivalent inertial effect. But locating mass very far away from its point of mechanical constraint (the main bearing) is inviting trouble in my estimation. Given that a platter must have a flat top, I think maybe a parabolically-curved underside, yielding a constantly varying thickness, might work well...something like this half-profile:
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(Sorry, the system doesn't permit the full illustration without justifying it, so imagine it mirrored with the bearing axis at the left margin.) Of course the bearing-point itself would be up inside the shape, slightly above its center of mass. Looking at this, I wonder if possibly the York TT that Fremer has sometimes pictured in his column might not have a similar platter profile, but I don't really know and can't think another myself. But if it does, that makes more sense to me than the common approaches. End of off-topic musings... |
Interesting stuff, I hope Teres comments on it. My own question at this point would be, what proportional contribution can we ascribe to the control system implemented on the DD, beyond the mere fact of the drive method itself? My own hunch is that this is where the greatest theoretical advantage of DD may lie, in affording the possibility of precision-designed platter control... BTW, in response to two points raised above: I suspect resonance is probably still somewhat more sonically determinative than speed distortions in modern high end designs; and when Twl writes: "I think it is because turntable designers all have varying degrees of understanding of the entire turntable system, and place varying amounts of emphasis on "perfecting" the various aspects, within a certain price range, and possibly with different technologies and approaches.
It is definitely not a foregone conclusion that just because a company makes turntables, that they are "expert" in the field. And even "experts" have holes in their knowledge base. And even if they do know everything(impossible), they cannot implement perfection, or even close to it at any affordable price range.
So, what you buy is inherently a compromise.
What types of compromising, and how well the compromises work as a whole, will determine the results" that about says it all, and if anything may be understating the case. With the proliferation of TT's these days, and especially moderate-to-mid-cost ones, my guess is that plenty are not really comprehensively "designed" at all, just aesthetically pleasing combinations of common elements, made and marketed to price points with full knowledge that they will never be technically scrutinized by the audio media, only subjectively compared to similar offerings. |
"I still stand by my remark that most audiophiles cannot hear pitch problems even when it hits them in their face" Then I guess it wouldn't shock you how many times there've been when I've gone to a seller's house to audition something or other for sale, and wind up informing the poor guy about which driver(s) ain't making any sound in which channel ;^) |
Tbg: Which post was I repsonding to? The last sentence of the last post prior to mine. (Read before I respond is always my motto!) I don't have perfect pitch; like most people I'm sensitive to relative pitch, but elasticity of pitch is one of the qualities which can give music a lot of its emotional power. Either way, speakers that rotate phase don't affect pitch, but yeah, it so happens my speakers don't rotate phase.
Dan: Was that you? Each time? Hey, I wouldn't have told anybody... |
Teres: Although my TT is made entirely of cast aluminum, I can relate to what you say, since I have guitars with bridges made of all these options: rosewood or ebony; brass; or cast aluminum; and in this application the first two definitely work better than the latter, which thins out tonality and reduces sustain. My only question would be, is what we're looking for in a guitar bridge necessarily the same thing we want in a turntable base (or platter)? Your listening tests would seem to answer that, although the number of well-regarded TT's using acrylic or aluminum would seem to reach a different conclusion (can you imagine a guitar bridge made of acrylic?). And it intrigues me that Nottingham uses cast iron and VPI uses stainless steel, both of which unlike brass seem vibrationally more inert. Then of course there's Rega's ceramic platter... |
